a machine for converting thermal energy into mechanical energy or power to produce force and motion.

a railroad locomotive.

a fire engine.

any mechanical contrivance.

a machine or instrument used in warfare, as a battering ram, catapult, or piece of artillery.

Obsolete . an instrument of torture, esp. the rack.

noun

agent , apparatus , appliance , barrel , contrivance , cylinder , diesel , dynamo , fan , generator , horses , implement , instrument , means , mechanism , motor , piston , pot * , powerhouse , power plant , power train , putt-putt , rubber band * , tool , transformer , turbine , weapon , [[what’s under the hoodnotes:engine is the more general term; motor is a special kind of enginean engine is a machine that converts potential energy into kinetic energy to provide motive force in order to do work; a motor is a small engine or a similar device powered by electricity]] , beam , booster , bypass , combustion , donkey , fuel injection , gasoline , induction , ion , jet , locomotive , mogul , newcomen , outboard , plasma , radial , ram , ramjet , retrorocket , steam , sustainer , synchronous , thruster , traction engine , turbojet , turboprop , v , vernier , wankel